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NJ Redevelopment Forum 2020 - Mahon

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Gabriel Mahon presentation.

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NJ Redevelopment Forum 2020 - Mahon

  1. 1. Stormwater Management Rules Applicability and Amendments Gabriel Mahon Bureau of Nonpoint Pollution Control Division of Water Quality New Jersey Department of Environmental Protection Presented at: 2020 Redevelopment Forum March 6, 2020
  2. 2. How is Post-construction Stormwater Managed in NJ? • Stormwater Management rules at N.J.A.C. 7:8 • Compliance required through permits issued by the NJDEP-Division of Land Use Regulation • Direct Implementation by NJDEP • Compliance required through MS4 Permits issued by the NJDEP-DWQ-Bureau of Nonpoint Pollution Control • Implementation by municipality • RSIS for residential projects • Stormwater Control Ordinance for non-residential projects
  3. 3. Amendments to Stormwater Management Rules • Dec. 3, 2018: NJDEP proposed amendments to the Stormwater Management rules. • Jan. 8, 2019: Public Hearing • Feb. 1, 2019: Close of 60-day public comment period • Dec. 3, 2019: NJDEP filed adoption package to OAL • March 2, 2020: Adoption of Rule • One year delayed operative date, effective 3-2-2021 • Current rules are in effect until 3-1-2021 • Same timeframe municipalities have to update ordinances in accordance with MS4 permits
  4. 4. What Projects Must Comply? • “Major Development” means an individual “development,” as well as multiple developments that individually or collectively result in: 1. The disturbance of one or more acres of land since February 2, 2004; 2. The creation of one-quarter acre or more of “regulated impervious surface” since February 2, 2004; 3. The creation of one-quarter acre or more of “regulated motor vehicle surface” since March 2, 2021; or 4. A combination of 2 and 3 above that totals an area of one- quarter acre or more. • If reviewed by the municipality • Through RSIS – ultimate disturbance of one acre or more • Through Stormwater Control Ordinance – as defined in ordinance (but must at least cover projects where the ultimate disturbance is one acre or more)
  5. 5. Rule Layout – Existing/Prior to Adoption SUBCHAPTER 5. DESIGN AND PERFORMANCE STANDARDS FOR STORMWATER MANAGEMENT MEASURES 7:8-5.1 Scope 7:8-5.2 Stormwater management measures for major development 7:8-5.3 Nonstructural stormwater management strategies 7:8-5.4 Erosion control, groundwater recharge and runoff quantity standards 7:8-5.5 Stormwater runoff quality standards 7:8-5.6 Calculation of stormwater runoff and groundwater recharge 7:8-5.7 Standards for structural stormwater management measures 7:8-5.8 Maintenance requirements 7:8-5.9 Sources for technical guidance
  6. 6. Rule Layout Re-arrangement SUBCHAPTER 5. DESIGN AND PERFORMANCE STANDARDS FOR STORMWATER MANAGEMENT MEASURES 7:8-5.1 Scope 7:8-5.2 Stormwater management measures for major development 7:8-5.3 Nonstructural stormwater management strategies GI 7:8-5.4 Erosion control, groundwater recharge and runoff quantity standards 7:8-5.5 Stormwater runoff quality standards 7:8-5.6 Calculation of stormwater runoff and groundwater recharge 7:8-5.7 Standards for structural stormwater management measures 7:8-5.8 Maintenance requirements 7:8-5.9 Sources for technical guidance
  7. 7. Rule Layout – As Adopted SUBCHAPTER 5. DESIGN AND PERFORMANCE STANDARDS FOR STORMWATER MANAGEMENT MEASURES 7:8-5.1 Scope 7:8-5.2 Stormwater management measures for major development 7:8-5.3 Green infrastructure 7:8-5.4 Groundwater recharge standards 7:8-5.5 Stormwater runoff quality standards 7:8-5.6 Stormwater runoff quantity standards 7:8-5.7 Calculation of stormwater runoff and groundwater recharge 7:8-5.8 Maintenance requirements 7:8-5.9 Sources for technical guidance
  8. 8. Means a stormwater management measure that manages stormwater close to its source by: 1. Treating stormwater runoff through infiltration into subsoil; 2. Treating stormwater runoff through filtration by vegetation or soil; or 3. Storing stormwater runoff for reuse. Green Infrastructure Definition N.J.A.C. 7:8-1.2
  9. 9. • GI BMPs must be used to satisfy recharge, quantity, and quality • Small-scale (limited drainage area) for recharge and quality • 3 Tables identifying the performance of each BMP in meeting the 3 standards • Table 5-1: Recharge, Quality, and Quantity Control • Table 5-2: Quantity Control • Table 5-3: Recharge, Quality, and Quantity Control ONLY with Waiver or Variance • Maintain existing ability to propose an alternative stormwater design. Alternative design must meet GI definition and must meet drainage area limitation if similar to BMP with limit. Green Infrastructure Standard N.J.A.C. 7:8-5.3
  10. 10. Best Management Practice Quality TSS removal rate (percent) Quantity Recharge Minimum separation from seasonal high water table (feet) Cisterns 0 Yes No - Dry Wells 0 No Yes 2 Grass Swales 50 or less No No 2 Green Roofs 0 Yes No - Manufactured Treatment Device (MTDs) 50 or 80 No No Dependent upon the device Pervious Paving Systems 80 Yes Yes No 2 1 Small-scale Bioretention Systems 80 or 90 Yes Yes No 2 1 Small-scale Infiltration Basins 80 Yes Yes 2 Small-scale Sand Filters 80 Yes Yes 2 Vegetative Filter Strips 60-80 No No - Table 5-1: BMPs for recharge, quantity, and quality Drainage area limitation applies to: dry wells, MTDs, pervious paving system, and small-scale bioretention, infiltration, and sand filters. Table 1 only includes MTDs that meet the definition of GI
  11. 11. Best Management Practice Quality TSS removal rate (percent) Quantity Recharge Minimum separation from seasonal high water table (feet) Bioretention Systems 80 or 90 Yes Yes No 2 1 Infiltration Basins 80 Yes Yes 2 Sand Filter 80 Yes Yes 2 Standard Constructed Wetlands 90 Yes No N/A Wet Ponds 50-90 Yes No N/A Table 5-2: BMPs may only be used for quantity Wet ponds used under Table 2 must be designed to have native vegetation and a reuse component
  12. 12. Best Management Practice Quality TSS removal rate (percent) Quantity Recharge Minimum separation from seasonal high water table (feet) Blue Roofs 0 Yes No N/A Extended Detention Basins 40-60 Yes No 1 Manufactured Treatment Device 50 or 80 No No Dependent upon the device Sand Filters 80 Yes No 1 Subsurface Gravel Wetlands 90 No No 1 Wet ponds 50-90 Yes No N/A Table 5-3: BMPs may only be used with waiver
  13. 13. • The water quality standard will apply to motor vehicle surface instead of impervious surface • Rule does not require roofs or sidewalks to be treated – consistent with current implementation • Requires pervious motor vehicle surfaces to be treated – consistent with scientific studies • Include in definition of major development • “regulated motor vehicle surface” Water Quality – Motor Vehicle Surface
  14. 14. • Added definition of “regulated motor vehicle surface” • Added definition of “regulated impervious surface” • Definitions of regulated motor vehicle surface and regulated impervious surface will include FAQ 10.2 (newly collected impervious surface and changes to existing drainage systems count as “new”) Definitions to Clarify Applicability N.J.A.C. 7:8-1.2
  15. 15. • Require quantity, quality, and groundwater recharge to be met in each drainage area on-site (unless they converge before leaving the property) • N.J.A.C. 7:8-5.2(l) • Move mounding analysis requirement from recharge standard to apply to all infiltration BMPs • N.J.A.C. 7:8-5.2(h) • Chapter 13 of BMP Manual Clarification of Applicability
  16. 16. BMP Manual Changes • Finalized new chapter on groundwater mounding (chapter 13) • Released draft for public comment • Revised chapter on calculations (chapter 5) • Allows infiltration in GI BMPs • Revised soil testing (chapter 12) • Adds new soil testing requirements for distributed GI systems • Revised model ordinance • Additional changes to BMPs coming when chapter 5 is finalized
  17. 17. • Updated Rules Adopted 3/2/2020 • One year delay in Operative Date to 3/2/2021 • Requirement to Use Green Infrastructure • Manage Stormwater Runoff close to its source • Drainage area limitations for GI BMPs • Updated/Revised Definitions • Clarifications • Meet Standards On-site • Mounding Analysis Summary

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